One problem related to tail light switch has been reported for the 2015 Tesla Model S. The most recently reported issues are listed below.
Head and tail lights turned off while driving on highway and would not turn back on. Neither high nor low beams would engage! a driver behind me saw what happened and turned on his high beams to guide me approx 1 mile to a safe stopping place. Once stopped, I experimented: hazard lights would turn on. No other lights turned on. I rebooted both the "mcu" (central 15" screen) and "ic" (instrument cluster) per earlier instructions from Tesla in case of automation failure in the car. The mcu took an extremely long time to restart and displayed screen corruption, problems which in the past had led Tesla to replace that component of this vehicle under warranty. When the mcu did start up, the instrument cluster displayed "driver assistance features disabled". I attempted to use Tesla's voice-activated "report" function to get help from Tesla, but this resulted in a message stating that "the microphone is being calibrated". This entire time, the head and tail lights remained off and would not turn on. Finally I used the mcu to access the lighting settings of the car. I observed that the "exterior lights" setting displayed "auto". However, it was 6:40pm and almost completely dark and the lights had been on previous to suddenly turning off. Also, with the "auto" setting, the high beams should still engage when pulling the left stalk - but this did not work. I next used this same screen to turn on the front fog lights. This worked! I then turned off the fog lights, changed the "exterior lights" setting to off then back to "auto" and all exterior lights (head and tail) finally came back on! it is my opinion, based on over 20 years in embedded software development, that the mcu's "exterior lights" setting had become corrupted and forced all vehicle lights off while I drove in darkness at 45mph. I could have died. Make Tesla fix this before someone dies!.